Very interesting idea. Definitely do it in body color.
I didn't love any of them, though. What about something a little more rounded, kind of like the outside taillight, maybe mirroring that curve. The Contour is kind of a curvy car... See photo for a QUICK & DIRTY mockup ! Reminds me of a Pre '98, so probably not what you were looking for.
Just an idea!
Post and let us know what you decide, and show a photo. Interesting idea !